The present invention relates to a sputtering target assembly having a precipitation hardened backing plate diffusion bonded to a sputtering target.
There has been growing interest in sputtering target assemblies with increasingly thin sputtering targets to reduce costs and, in some cases, accommodate the sputtering target assembly in certain sputtering chambers. In such applications, sputtering target assemblies of less than about one inch total thickness may be required. However, with such sputtering target assemblies, the strength of the backing plate may be exceeded under the conditions encountered in the sputtering chamber, which may include high water pressure on one side for cooling and high vacuum on the other side during the sputtering process. Thermal cycling and pressure resulting from circulating coolant exerted upon the backside of the target assembly with simultaneous vacuum conditions on the front face of the target can result in elastic and plastic deformation of the target backing plate assembly.
Although sputtering target assemblies may be made by solder bonding backing plates of various materials to a target, solder bonding has the disadvantage of not being able to withstand high power sputtering applications. Thus, diffusion bonded sputtering target assemblies are preferred.
The present invention provides a method of making a sputtering target assembly with a high strength backing plate diffusion bonded to a sputtering target that can withstand the stresses and strains typically encountered in sputtering chambers.